条件变量 学习笔记

 1 #include <stdio.h>
 2 #include <stdlib.h>
 3 #include <unistd.h>
 4 #include <errno.h>
 5 #include <pthread.h>
 6 #include <semaphore.h>
 7 
 8 #define ERR_EXIT(m) do { perror(m); exit(EXIT_FAILURE);} while(0)
 9 
10 int pNum = 0;
11 pthread_mutex_t lock;
12 pthread_cond_t cond;
13 void init()
14 {
15     int ret;    
16     ret = pthread_mutex_init(&lock , NULL);
17     if(ret != 0) {
18         ERR_EXIT("pthread_init");        
19     }
20     ret = pthread_cond_init(&cond, NULL);
21     if(ret != 0) {
22         ERR_EXIT("pthread_cond_init");        
23     }
24 }
25 void *consumerFun(void *arg)
26 {
27     while(1) {
28         pthread_mutex_lock(&lock);
29         while(pNum == 0) {
30             printf("wait product exit...\n");
31             pthread_cond_wait(&cond, &lock);    
32         }
33         printf("already exit ...\n");
34         pNum--;
35         printf("consumer pNum %d\n", pNum);
36         pthread_mutex_unlock(&lock);
37         sleep(1);
38     }
39     return (void *)0;    
40 }
41 void *producerFun(void *arg)
42 {
43     while(1) {
44         pthread_mutex_lock(&lock);
45         pNum++;
46         printf("producer product one :%d\n", pNum);
47         pthread_cond_signal(&cond);
48         pthread_mutex_unlock(&lock);
49         sleep(3);
50     }
51     return (void *)0;    
52 }
53 int main(int argc, char *argv[])
54 {
55     int ret;    
56     pthread_t producer;
57     pthread_t consumer;
58     init();
59     ret = pthread_create(&producer, NULL, producerFun, NULL);
60     if(ret != 0) {
61         ERR_EXIT("pthread_create");        
62     }
63     ret = pthread_create(&consumer, NULL, consumerFun, NULL);
64     if(ret != 0) {
65         ERR_EXIT("pthread_create");        
66     }
67     pthread_join(producer, NULL);
68     pthread_join(consumer, NULL);
69     pthread_mutex_destroy(&lock);
70     pthread_cond_destroy(&cond);
71     return 0;    
72 }